Spring for urging outward the vanes of vane type hydrodynamic machines



March 24, 1953 w. FERRIS 2,632,398

SPRING FOR [meme ouTw THE VANES 0F VANE TYPE HYDRODYNA c MACHINES 2SHEETS-SHEET 1 Filed Dec. 5, 1946 I INVENTOR. WALTER FERRIS WW ATTORNEYMarch 24, 1953 w. FERRIS 2,632,398 SPRING FOR URGING OUTWARD THE VANESOF VANE TYPE HYDRODYNAMIC MACHINES 2 SHEETS-SHEET 2 Filed Dec. 5, 1946IN VEN TOR.

WALTER FERRIS ATTORNEY Patented Mar. 24, 1953 SPRING FOR URGING OUTWARDTHE VANES OF VANE CHINES TYPE HYDRODYNAMIC MA- Walter Ferris, Milwaukee,Wis., assignor to The Oilgear Company, Milwaukee, Wis., a corporation ofWisconsin Application December 5, 1946, Serial No. 714,248

3 Claims.

This invention relates to hydrodynamic machines of the sliding vanetype. Such a machine includes a rotor which is enclosed in a chamberhaving inlet and outlet ports for the flow of liquid to and from therotor, a plurality of vanes which are slidable in slots extending inwardfrom the periphery of the rotor, and an endless vane track which extendsaround the rotor to engage the outer ends of the vanes.

The vane track may be stationary, in which case the displacement of themachine is constant, or it may be adjustable to vary the displacement ofthe machine. If the vane track is stationary or if it is adjustable andthe machine is adjusted to perform useful work, a portion of the vanetrack adjacent one end of each port is arranged close to the peripheryof the rotor and a portion of the vane track adjacent the other end ofeach port is spaced farther from the periphery of the rotor so that thevanes are caused to move inward and outward of the rotor as the outerends thereof ride upon the vane track during rotation of the rotor.

Sliding vane type hydrodynamic machines are in extensive use as pumpsbut such a machine may be employed as a motor if it is properlydesigned. In either case, the outer ends of the vanes must remain firmlyin contact with the vane track as they pass from each port area to theadjacent port area, as otherwise the machine would fail to function, andit is practically essential that the outer ends of the vane continuouslyengage and follow the vane track in order to obtain quiet andsatisfactory operation of the machine.

A pump is ordinarily operated at such high speed that it is onlynecessary to hydrostatically balance the vanes as the centrifugal forcewill hold the vanes in contact with the vane track but a motor is oftenstarted under load and is often operated at such low speed that thecentrifugal force is insufiicient to hold the vanes in contact with thevane track. Therefore, if the machine is to function as a motor or is tofunction as a pump and be driven at low speeds, means must be providedfor holding the vanes in contact with the vane track and in a motor thevanes must be in contact with the track before the motor is started.

The vanes of a machine have heretofore been held in contact with thevane track by supplying to the inner ends thereof liquid at a pressurehigher than the pressure of the motive liquid as shown, for example, inPatent No. 2,335,567. A machine provided with such a system is entirelysatisfactory from an operating standpoint but the mechanism forsupplying high pressure liquid to the inner ends of the vanes addsconsiderably to the cost and to the overall dimensions of the machine.

It has also been proposed to provide vane type machines having springsfor urging the vanes into engagement with the vane track but as far asis known no such proposed machine was capable of meeting commercialrequirements, particularly as to machines for use with liquid and foroperating at high pressures such as at or above 1000 p. s. i.

The present invention has as an object to provide a vane typehydrodynamic machine having novel spring means for urging the vanes intoengagement with the vane track.

Another object is to provide a vane type hydrodynamic machine which willoperate successfully at low speeds as well as at high speeds and underhigh or low pressure and which has overall. dimensions substantially nogreater than those of similar vane type machines which are capable ofoperating only at high speed.

Another object is to provide a vane type hydrodynamic machine which hassprings for urging its vanes against its vane track and which is capableof operating successfully in commercial use for a very long period oftime.

Other objects and advantages of the invention will appear from thefollowing description of the hydrodynamic machine illustrated in theaccompanying drawings in which the views are as follows:

Fig. 1 is in part an elevation of and in part a transverse sectionthrough a machine in which the invention is embodied, the section beingtaken on the irregular line l| of Fig. 2.

Fig. 2 is a longitudinal section taken along one face of the rotor asindicated by the line 22 of Fig. 1.

Fig. 3 is an enlarged view of the vane and the vane spring shown in theupper part of Fig. 1.

Fig. 4 is a section taken on the line 44 of Fig. 3.

Fig. 5 is a face view of one of the cheek plates, the View being takenon the line 5-5 of Fig. 1.

Fig. 6 is a diagram of the circuit for supplying liquid to the innerends of the vane.

Fig. 7 is a view somewhat similar to Fig. 3 but showing the springreversed.

Fig. 8 is a, view taken at right angles to Fig. 7.

The machine chosen for illustration is of the general type shown inPatent No. 2,335,567 to stood that the invention is equally applicableto I both pumps and motors and to both constant and variabledisplacement machines.

As shown, the motor has its mechanism arranged within a casing I havingtwo connections 2 and 3 by means of which the motor may be connectedinto a hydraulic circuit and Which may function interchangeably as theinlet (and outlet of the motor.

Casing I has a circular chamber 4 formed :therein and closedbyaremovable end head 5;

Ghamber hasa spacefring 6 fitted therein between two cheelrjplates T-and8 which engagethe inner wall of chaniberfli' and the inner face of head5 respectively; Spacer ring 6 and cheek plate I and enclose a circularrotor 9 which is fixed for rotation with a shaft Hand is just enoughthinner than spacer ringt to permitit to rotate freely between cheek pltes I and 8 and at the's ame time maintain substantially liquid tightseals bctw'e en'its opposite faces and the cheek plates. Shaft Itextends outward through casing I for connection to 'adeviceto bedrivenand it is rotatably supported by, suitable bearings, one bearing beingshown at I I;

o or 9 has a ur i y oir ne's I5 extending inward from its peripheryandavane I6 slid- ,ably fitted in each slot. The outer ends" of vanes I6engage anendlessvane track iTwhich in the presentinstance has been shownas being formed l b'oflihe' inner periphery of acer r n ,6 but which maybeatseparate structure and be adjustable in any suitable manner to varymotor displacement such, for example, as shown in Patent e-2 3069,-

In the embodiment shown, vane track I! is ap proxima ly i t c and'ametrica QPPbS a '3 n the $51 115 Q t lea d mc and two diametricallyopposed arcs I9 in the reeiqns Q t ate t d eme A s 8 e preferably butnot necessarily concentric with rotor 9 andere de i a e erein a se l n rs A 1% e d s ated he ein as Wo a c an p ifif i r bl a n y y? not ui e cn tri w th r torv 9 o th t the rt ons of v e ack ll intermediate arcs I8 and I9 may be given a curvature which will produce, satisfactory ratesof inward and outward movements of vane I6 as rotor 9 rotates. Thelengthof each arc l and I9, is at least as great as the angular distancebetween the outer ends of two adjacent'vanes I6.

In order that the hydraulic forces actin upon rotor 9 in radialdirections may be balanced, the space between'vane track I! and theperiphery or rotor Sis divided intdt'wo equal and diametrically opposedfluid sections by the vanes I 6 in contact withsealing' arcs I3, andeach fluid section isdivided into an inlet area and an outlet area bythe vane 'or vanes in contact with working arc I9.

'Motive liquid is admitted between the outer ends of the van'es as theypass through the inlet areas, and this motiteliquid acts upon the vanesin contact with the workingarcs I9 and effects rotation of rotor 9. Ifthe machine were to operate as apump, rotorj 9 would be rotatedmechanically andthetvanes would transfer liquid from the inlet 4 areasto the outlet areas as they passed across working arc I9.

Cheek plate 1 has two diametrically opposed ports 29 and twodiametrically opposed ports 2| formed therein adjacent the periphery ofrotor 9. Each port 29 extends from a point near one end of an arc I9 to"a pointnear the adjacent end of an arc I8 and each port 2i extends froma point near the other end of arc I9 to a point near the adjacent end ofthe other are I8. Both ports 2i) communicate with an arcuate passage 22which is formed in casing I and communicates with connection 2 through apassage not shown. Both ports 2| communicate with an arcuate passage 23which is formed in casing I and communicates with connection 3 through apassage not shown.

Ports 29 and 2 I may function interchangeably asinlet and outlet portsand the space between vane track I? and rotor 9 adjacent each port maybe designated an inlet area if that port is functioning as an inlet portor designated an foutlet area if th'at'portis functioning a anoutlet'port.

vCheek plate 3 is also plbvid d with ports 20 and 2t each or which is inaxial alinernent with the corresponding port incheek'plate'l so that allhydraulic forces acting assurance 9 in an axial direction'are balanced."n

As vanes 'I'o move inward and outward in slots 15 during rotation Ofrotor 9,lid1 i'd 'willifiow into each van-e slot as the vanetherein'moves outward and liquid will be expelled from each'vane'slot as thevane therein moves inward. In brd'eiito provide for'this' flow of liquidto and from the vane slots and" also to hydrostatically balance thevanes as the outer ends thereof pass through the inlet and outletare'as;eacliof cheek plates I and8"'has"twoarcuate groovesor viane slot ports24 and two arcuatgrooves or'van-e'slot ports 25 formed in its'inne'r wasupon a radius equal to the radius of the inner "ends ofvane slots I 5 sothat vane slots I5 'will'reg'ister successively with'the vane slot portsas rotor 9 rotates; "Each vane slot port 24 is radially inwardffro'm aport 20 and is connected thereto by a'gmove 26 formed in the outer faceof the cheek plate. Each vane slot'port 25 is radially inward "from aport'2l and is connected thereto by a groove 27 formed in the outer faceof the'cheek plate." The arrangement is such that both the inner andouter ends of the'vanes are subjected tothe same pressure when the outerends of the vanes aremovmg through'tl'ie inlet areasand whentheouterends" of the vanes arernoving through the outlet areas'so' that the"vanes "may be kept in contact'with "the 'vanetrack' by application of arelatively small radial force.

"I dc ha he Whose ou en s are in contact with the arcs I8 and I9 mayhave their inner ends subjected to pressure, each of cheek plates 7 and8 has formed in the inner face thereof two vane slot orts 28, each ofwhich is radially inward from a sealing arc I8 and is mid-way betweenthe adjacent ports Hand 25, and two vane slot ports 29 each of which isradially inward from a Working arms and is midway between the adjacentports' 26 and 25. Ports 28 and 29 are supplied with liquid from a port2ll'or a port 2 'I whichever is ahig hpressure port. As shown, all fourof the portsf' 25 and 29 in cheek late 8 communicate with a groove 30which'is formed in the outer face of cheek'plate s and communicates witha channel 3I having two branches 32 and 33 which are connected,respectively, through, a valve 34, and Ya channel '35 we port andthrough a valve 36 and a channel 37 to a port 2|.

Valves 34 and 36 may be ordinary check valves, in which case thepressure in ports 28 and 29 is the same as in high pressure port 20 or2|, but valves 34 and 33 preferably are pressure reducing valves as willpresently be explained.

A vane in contact with a sealing arc I8 or a working arc l9 has one sidethereof subjected to the workin pressure and the other side thereofsubjected to the exhaust pressure which ordinarily is zero or so low asto be negligible. If a vane in contact with a sealing or working arcwere stationary and the exhaust pressure were zero, the film of liquidunder the vane would have a pressure which would be equal to the workingpressure at one side of the vane and would decrease to zero at the otherside of the vane so that the force tending to move the vane inward wouldbe equal to the cross-sectional area of the vane multiplied by one-halfof the working pressure and the vane could be hydrostatically balancedby subjecting its inner end to a pressure equal to one-half of theworking pressure.

However, it has been found in practice that the forces required to holdthe vanes in contact with the sealing arcs and the working arcs aregreater when the machine is operating than when the machine is idle. Forexample, when a machine is operating under certain conditions, the forcetending to lift a vane off from a sealing are or a workin arc is equalto the cross-sectional area of the vane multiplied by approximately 70%to 80% of the working pressure.

The force for holding the vanes against the vane track should exceed thelift-off force but, if a vane in contact with a sealing are or a workingarc had its inner end subjected to full working pressure which would bethe case if channel- 3| were connected to ports 20 and 2| through checkvalves, that vane would be urged against the working or sealing are by aforce equal to the difference between the hold-on and the lift offforces.

In the above example, if the pressure of the motive liquid were 1000 p.s. i. and each vane were .13" thick and 1" wide which is a common sizevane, the hold-on force would be 130 pounds and the lift ofi force wouldbe 91 pounds. Therefore the vane would bear upon the sealing or workingarc with a force of 39 pounds which would be a greater force than couldbe safely supported by the small area of film under the end of the vaneand might cause excessive wear or gallin of the vane and/or the vanetrack.

It is therefore desirable to reduce this bearing force and this mayreadily be accomplished by providing valves 34 and which will reduce thepressure in vane slot ports 28 and 29 a predetermined amount such as 20%which under the conditions outlined above would reduce the bearing forceby two-thirds.

As shown, valve 34 includes a casing having a bore 4| and a counterbore42 formed therein, a valve 43 fitted in bore 4|, piston 44 fitted incounterbore 42 and ordinarily formed integral with valve 43, and a lightspring 45 arranged between piston 44 and the end wall of counterbore 42to normally hold Valve 43 in its closed position and having only alittle more strength than is necessary to overcome the friction andinertia of valve 43 and piston 44. Bore 4| has channel 35 connectedthereto adjacent the end thereof. It has branch 32 of channel 3|connected thereto at such a distance from its end 6 that valve 43 blocksthe end of branch 32 when valve 43 is in its closed position, andcounterbore 42 has channel 3| connected thereto adjacent the endthereof.

Since valve 36 is exactly the same as valve 34 except that it haschannel 31 and branch 33 connected thereto instead of channel 35 andbranch 32, a description of one will suifice for both as correspondingparts have been designated by corresponding reference numerals with theexponent a added to the reference numerals applied to valve 36.

The arrangement is such that, when pressure increases in port 20,pressure will extend therefrom through channel 35 to bore 4| and shiftvalve 43 against the resistance of spring 45. As soon as valve 43 startsto uncover the end of branch 32 of channel 3|, pressure willextendthrough channel 3| to ports 28 and 29 and also to the counterbores 42and 42 The pressure in counterbore 42 will act upon piston 44 and tendto close valve 43 and the pressure in counterbore42 will act upon piston44 and cause it to assist spring 45 in holding valve 43 closed.

Valve 43 and piston 44 are so proportioned that,

when port 20 is a high pressure port, valve 34 maintains in ports 28 and29 a pressure equal to a given percentage of the pressure in port 20.For example, if it is desired that the pressure in ports 28 and 29 be20% less than the working pressure, valve 43 and piston 44 are soproportioned that the force exerted upon valve 43 by the working liquidwill be balanced by the forces exerted on piston 44 when the pressure incounterbore 42- is of the working pressure. Therefore, an increase inthe working pressure or a decrease in the pressure in counterbore 42will cause the valve 43 to open and a decrease in working pressure or anincrease in the pressure in counterbore 42 will cause the valve 43 toclose so that the pressure in counterbore 42 and also in ports 28 and 29is maintained at substantially 80% of the working pressure.

When port 2| becomes the high pressure port, valve 33 opens to admitpressure to ports 28 and 29 and to counterbores 42 and 42, the pressurein counterbore 42 assisting spring 45 in holding valve 43 closed.Thereafter, the pressure in ports 28 and 29 is maintained at a givenpercentage, such as 80%, of the working pressure by valve 36 whichoperates in the same manner that valve 34 operates when port 20 is thehigh pressure port.

It has been previously explained that the outer ends of the vanes mustremain continuously in contact with the vane track in order to obtainquiet and satisfactory operation of the machine, that the vanes arehydrostatically balanced as the outer ends thereof pass through theoutlet and inlet areas, and that the present invention provides springsfor maintaining the outer ends of the vanes in contact with the vanetrack.

The greatest difficulty encountered in providing springs for holding thevanes against the vane track is due to the necessity of arranging both avane and a vane spring in a vane slot which is very small. A common sizerotor is a little less than 1" thick and has vane slots which are about9 64" wide and extend radially inward about A". Each vane slot is thusonly about 1" by A by 934"- If the vane slots were extended fartherinward from the periphery of the rotor, the metal between the inner endsof the adjacent slots would be reduced which would weaken the rotor atthe subjected to high pressure liquid on one side thereof and to lowpressure liquid on the other side thereof. -If the size of the vane slotwere increased by increasing the diameter of the rotor,

the size, weight and cost of the machine would be increased without acorresponding increase in volumetric capacity.

It is thus desirable that the springs be added without altering the sizeof the vane slots but the space available for each spring is very smallp r c la w n he e is n it e rem i war p it n- Th e e e ch s r ng m s beverysmall and it must have a great deflection relative to its size dueto the distance through which the vane moves radially. Also, the springmust be capable of moving a vane outward and holding it against the vanetrack when the compression of the spring is the least.

The vane springs must therefore be very small but, by hydrostaticallybalancing the vanes as the outer ends thereof pass through the inlet andoutlet areas so that the force required to move a vane radially is verysmall, a spring having sufficient strength to move a vane outward andhold it against the vane track may be inserted in each vane slot byforming a notch in the inner end of each vane to provide a space for thespring.

As best shown in Fig. 3, each vane !B has a notch 50 formed in the innerend thereof to provide a space for a spring and to retain spring 5! inposition in vane slot !5. Spring 5! includes two spaced apart torsioncoils 52 and 53 which are relatively large in diameter and have the axesthereof normal to the radial path of vane l6, an intermediate section 55connecting coils 52 and 53 to each other and holding them in spacedrelation, and two spring arms 55 and 55 extending from coils 52 and 53respectively. The free ends of arms 55 and 56 are curved and flattenedand are adapted to slide upon the inner end of vane slot !5 as spring 5!is compressed and expanded by radial movements of vane 5.

Spring 5! may be formed by arranging two mandrels of the proper diameterin fixed positions the proper distance apart and winding a length ofsmall diameter spring wire around one mandrel to form a tight coil 52and then winding the wire around the other mandrel to form a ti ht coi53- 'Ihe e' Wound n, t s e rec e ermine b. end s hat a 55 extends fromone end of coil 52 and arm 55 extends irom he o posi n o coil e mediatesection 54 is bent adjacent each coil an amount sufiicient to bring thetwo coils into the same plane and each of arms 55 and 5B is bent at ornearits junction with a coil to cause the arm to slope toward the otherarm.

The length of each of coils 52 and 53 is less than the width of a vaneslot. For example, if the vane slot is wide, spring 5! may be formedfrom .023 diameter spring wire and each coil may consist of four turnsso that each coil is long which allows clearance between the ends of thecoils and the walls of the vane slot.

In a machine having two fluid sections as shown in Figs. 1 and 2, eachvane spring is compressed and expanded twice durin each revolution ofthe rotor. Hydraulic motors are often operated for long periods of timeat 1000 iii R. P. M. or more. At 1000 R. P. M., each vane spring will beflexed 2000 times per minute which amounts to nearly one, millionflexings in one work day of eight hours. A vane spring to be successfulmust, therefore "be capable of being flexed through a wide range withgreat rapidity and of withstanding many millions of flexings.

If a vane spring were constructed without torsion coils or with torsioncoils of relatively small diameter, the greater part of the flexing ofthe spring would occur in very limited sections of the wire and themetal in those sections would become fatigued and cause the spring tofail after the machine had been in use only a short time.

However, in a spring having torsion coils of relatively large diameteras shown, the greater part of the flexing is distributed throughout muchgreater sections of the wire which enables the spring to be flexed withgreat rapidity and to have a long life. In fact, springs constructed asshown appear to be in perfect condition after being taken from a motorwhich had been run for long periods of time during which each spring wasflexed several million times.

As spring 5! is compressed and expanded in response to inward andoutward movements of vane !5, the ends of arms 55 and 55 slide back andforth upon the bottom of vane slot !5. In order to avoid undue wear ofarms 55 and 55 due to these sliding movements, the bottom of slot I5 andthe curved and flattened ends of arms 55 and 55 are polished to reducethe friction therebetween. Since the inner end of each vane slot alwayscontains some of the working liquid which almost invariably is a goodgrade of oil, the friction between the bottom of vane slot i5 and theends of arms 55 and 55 is negligible.

Inward and outward movements of vane !5 also causes coils 52 and 53 tomove radially in slot :5 but the length of each coil is less than thewidth of slot !5 as previously explained, there is no force urging coils52 and 53 against either wall of slot !5, the walls of slot I5 are madefiat and smooth to reduce the friction between them and vane E5, and thewalls of slot !5 are well lubricated by the working liquid. Therefore,there is substantially no abrasion of the ends of coil 52 and 53.

However, all danger of abrading the ends of coils 52 and 53 may beavoided by reversing spring 5! as shown in Figs. '7 and 8. That is,coils 52 and 53 may be supported upon the bottom of vane slot !5 and theends of arms 55 and 56 caused to slide upon the end wall of notch 55.

Spring 5! is normally centered between the two sides of rotor 9 and, ifit should move axially of rotor 9, the ends of one of arms 55 and 56would engage a side wall of notch 50 and shift spring 5! back towardcenter. However, it is desirable to keep spring 5! centered and this maybe accomplished in various ways such as by forming in the bottom of vaneslot 15 a, recess 5'! to receive spring 5i and to restrain it from anysubstantial movement axially of rotor 9.

Recess 5'! may be formed in any suitable manner but, since it is commonpractice to form a small round hole at the inner end of each vane slotas shown in Fig. 2, recess 5'! may be provided by a counterbore 58, asindicated by the dotted circle in Fig. 8. The depth of recess .5! hasbeen exaggerated in the drawings for the purpose of illustration butonly a very shallow recess is required to restrain spring from movingaxially of rotor 9.

With the vane spring reversed as shown in Figs. 7 and 8, the torsioncoils do not move radially in response to radial movements of the vanes.Therefore, no abrasion of the coils can occur.

The invention herein set forth is susceptible of various modificationswithout departing from the scope of the invention which is herebyclaimed as follows:

1. A spring for urging radially outward a thin vane which has a bearingsurface on its radially inward edge and is fitted in a narrow slot whichis formed in the rotor of a hydrodynamic machine and has a bearingsurface at its radially inward end, said spring being formed from asingle strand of small diameter spring wire and comprising two torsioncoils of such lengths that said spring can flex freely when arrangedWithin said slot, an intermediate section connecting one end of one ofsaid coils to the opposite end of the other coil to hold said coils inspaced relation and in position to bear upon one of said surfaces, andan arm extending from the other end of each of said coils outward andtoward the other coil to engage and slide upon the other of saidsurfaces as said vane moves radially in said slot.

2. A spring for urging radially outward a thin vane which has a bearingsurface on its radially inward edge and is fitted in a narrow slot whichis formed in the rotor of a hydrodynamic machine and has a bearingsurface at its radially inward end, said spring being formed from asingle strand of small diameter spring wire and comprising two torsioncoils arranged in the same plane and each formed by at least three turnsof said strand and having a length less than the width of said slot, anintermediate section connecting one end of one of said coils to theopposite end of the other coil to hold said coils in spaced relation andin position to bear upon one of said surfaces, and an arm extending fromthe other end of each of said coils outward and toward the other coil toengage and slide upon the other of said surfaces as said vane movesradially in said slot.

3. A spring for urging radially outward a, thin vane which has a bearingsurface on its radially inward edge and is fitted in a narrow slot whichis formed in the rotor of a hydrodynamic machine and has a bearingsurface at its radially inward end, said spring being formed from asingle strand of small diameter spring wire and comprising two torsioncoils adapted to engage one of said surfaces and of such lengths thatsaid spring can flex freely when arranged within said slot, anintermediate section connecting one end of one of said coils to theopposite end of the other coil to hold said coils in spaced relation andso shaped that it holds the corresponding ends of said coils in the sameplane, and an arm extending from the other end of each of said coilsoutward and toward the other coil to engage and slide upon the other ofsaid surfaces as said vane moves radially in said slot.

WALTER FERRIS.

REFERENCES CITED The following references are of record in the file ofthis patent:

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